<template functional>
    <div>
        <h2>函数式组件</h2>
        <div>纯UI组件</div>
        <h3>props</h3>
        <div>{{props.p1}}</div>
        <h3>事件</h3>
        <button @click="parent.show(123)">parent事件</button>
    </div>
</template>